Step into A&E, Fred (7)
I believe the answer is:
'fred' is the definition.
(I've seen this in another clue)
'step into ae' is the wordplay.
'step' becomes 'stair' (a single step in a staircase).
'into' is an insertion indicator.
'stair' placed into 'ae' is 'ASTAIRE'.
(Other definitions for astaire that I've seen before include "Fred -, twentieth century US dancer" , "A satire about Fred, great Hollywood dancer" , "US dancer (Top Hat)" , "Fred --, dancer/actor" , "dance performer" .)